Abrasive cutting wheel



Aprll 1l, 1961 H. sHoENMAKERs ABRAsIvE CUTTING WHEEL Filed April 25. 1958 Wvmm//////////f/////l//4 V///////////, L

INVENTOR HENDRIKUS SCH OENHAKERS AGENT United States Patent() ABRAslvE cU'rrrNo WHEEL Hendrikus Schoenmakers, Eindhoven, Netherlands, as. signor to North American Philips Company, Inc., New York, N.Y., a corporation of Delaware Filed Apr. zs, 195s, ser. No. 130,886 claims priority, application Netherlands nee. 24, 1951 z claims. (ci. 51-206) This invention relates to an abrasive cutting wheel, the sides of which are provided through a certain area with bonded diamond grains and which is used for sawing into f, lengths hard materials, more particularly glass tubes and 'v rods. Such abrasive cutting wheels are expensive tools capable of cutting rapidly and accurately, however, they have a limitation in that they glaze comparatively rapidly under certain conditions. One can continue cutting with such a glazed Wheel, however, wear of the wheel will be great and there will be a high reject percentage of the product, since the wheel wobbles slightly; the sizes of the severed lengths are no longer the same and the end faces are chipped and no longer at right angles to the longitudinal axes. It was surprising to find that a much higher output with a smaller reject percentage can be obtained with such a cutting wheel, if in accordance with the invention the wheel is designed so that the cutting surfaces are provided not only with the inherent recesses, but also with a number of further small recesses which preferably are distributed irregularly.

In one embodiment of the invention the recesses made deliberately are shaped conically with an apical angle of preferably 60.

'I'he eiciency and the life of the cutting wheel are found to be particularly increased if, in another embodiment of the invention, at the most about 15 recesses are provided per cm.2 of the cutting surface.

It is not necessary for the entire cutting surface on both sides of the wheel to be provided with recesses. Satisfactory results are obtained also if according to a further embodiment of the invention the cutting surface on one side is divided in an even number of imaginary equal sectors every other one of which is provided with recesses, while the cutting surface on the other side is divided in an equal number of similarly arranged imaginary sectors, the recesses on this side being provided in sectors staggered with respect to the other side. This 'embodiment of the invention is particularly advantageous, if the recesses have to be provided in a finished wheel, since with this arrangement the wheel is less likely to warp due to the provision of the recesses.

In a cutting wheel in Iaccordance with the invention, which is made of metal, has a maximum thickness along the cutting surfaces of 1 mm. and a maximum diameter of 200 mms., the irregularly `arranged recesses deliber- Iately provided in the cutting surfaces according to a further embodiment of the invention have a depth of about 0.2 mm. A

In order that the invention may readily be carried out,`one embodiment thereof willinow be` described'more fully with reference to the accompanying drawing, in which: l

Fig. l is a sectional view taken along the centre line e of a cutting wheel provided at the sides with bonded diamond grains,

of part of a s ide of Fig. l,

` the cutting surfaces were worn off entirely. Every hour 1o Fig. 2 shows on a greatly enlarged scale an elevation l'conical in shape with an apical angle of approximately 2,978,847 Patented Apr. 11,- 1961 ICC Fig. 3 shows likewise on a greatly enlarged scale part of 'the sectional view according to Fig. 1, and

Fig. 4 is a side view of a cutting wheel of the kind shown in Fig. l.

In the figures, reference numeral 1 designates a metal wheel which is secured to a shaft 3 in known manner by two clamping means 2. At` its circumference the wheel is provided on either side with a cutting surface 4 comprising bonded diamond grains. As is shown more clearly in Figs. 2 and 3, recesses 6 are provided between diamond grains 5. In a wheel having a diameter of at the most 200 mms. and a thickness along the cutting surfaces of at the most 1 mm., these recesses have a depth of about 0.2 mm., provision being made of at the most about 15 recesses per cm.2 of the cutting surface. In practice it is found that such a wheel provides a much higher output than a non-recessed wheel. As an example a wheel having -a diameter of mms. and a thickness along the cutting surfaces of 0.8 mm. may be used. The width of the cutting surfaces was l() mms. Prior to the provision of the recesses there could be cut from glass tubing having an outer diameter of 4.5 mms. and a wall thickness of from 0.7 to 0.9 mm. 8000 lengths per hour for 40 hours. The reject percentage was about 10 percent owing to oblique end faces and chipping. At the end of 40 hours of cutting required an hour of sorting. The high reject percentage and the wear of the wheel were due to the fact that the cutting surfaces became glazed so that the cutting effect was reduced and furthermore the wheel tended to wobble in operation. Due to the reduction in the cutting action a higher amount of energy was required which again increased the wear. In operation a water jet was continuously directed onto the product and the wheel. After the provision of the recesses a similar disc could cut slightly more than 12,000 lengths per hour from tubing of glass of the same kind and having the same dimensions for 60 hours under the same operating conditions; the reject percentage was negligible and certainly less than 1 percent. Sorting, which under the previously mentioned conditions would have taken 3 hours for 12,000 lengths, could be omitted. Presumably the grindings mainly nd their way into the recesses from which they are washed by the water jet, so that the cutting surfaces do not become glazed.

Fig. 4 is a-side view 0f a cutting wheel in which the cutting surfaces 4 are divided in ten imaginary sectors. In tive sectors 8 recesses are provided, the remaining sectors 7 not being recessed. The cutting surface on the other side of the wheel is divided in the same number of sectors; here, however, the recesses are provided in the sectors registering with the sectors 7 while the sectors registering with the sectors 8 are not recessed. 'I'his arrangement is Aof advantage when a normal commercially available disc is provided with recesses since the disc is'less liable to warp due to the recessing.

The invention is not only highly advantageous in cutting glass tubes `and glass rods but abrasive cutting wheels deliberately provided with recesses in accordand with the invention can also be used to advantage in cutting ceramic tubes and yrods and in general in cutting all hard materials for which diamond bonded cutting wheels are used.

What is claimed is:

l. A grinding wheel having cutting surfaces provided with a multiplicity of abrasive grains bonded to said wheel for' cutting relatively hard materials into predetermined lengths, the cutting surfaces of said grinding `i60, nthe "cutting, "surface on lone side of said grinding vwheel having said recesses yin spaced sections therein,

References Cited in the rilerof this patent UNITED STATES PATENTS Puffer 1 July 6, 1909 Gardner et al Jan. 11, 1910 Johnston Nov. 5, 1935 Webster Apr. 7, 1936 ,Van der Pyl Feb. 23, 1937 Albertson May 20, 1941 Kelleric Mar. 112, 1957 Hr'st -.r.-..--..1.. Sept. 3, 1957 

